In recent years, in the field of manufacture of electronic devices represented by the manufacture of integrated circuit devices, requirements for high integration of devices are increasing, and it is known that the structure of a polymer in a photoresist composition influences the formation of a fine pattern.
In the photoresist composition, lithography properties such as sensitivity to an exposure light source, resolution capable of forming a pattern having fine dimensions, and the like are required, and therefore, Chemically amplified photoresist compositions composed of an acid dissociable functional group-containing polymer and a compound capable of generating an acid upon irradiation with radiations (hereinafter referred to as “exposure”) (the latter compound will be hereinafter referred to as “photo acid generator”) is used. The acid dissociable functional group-containing polymer is based on a structure in which a part of an alkali easily soluble site of an alkali soluble polymer is protected by an appropriate acid dissociable functional group, and the selection of such an acid dissociable functional group is very important in view of regulating a function as a photoresist composition.
As the already-known acid dissociable functional group-containing polymer which is incorporated into the photoresist composition, for example, there are known polymers obtained by polymerizing a material containing an adamantyl group-containing acrylic ester (see Patent Document 1); polymers having, as a constituent unit, a lactone skeleton-containing acrylic ester introduced thereinto (see Patent Document 2); polymers having a norbornane lactone skeleton-containing constituent unit (see Patent Documents 3 to 5); and the like.